1. Field of the Invention
This invention relates to a slide fastener and a method of making the same. More particularly, the invention is concerned with such a slide fastener which carries thereon coupling elements formed from a thermoplastic material into a discrete structure and which finds wide application on jackets, trausers, shirts, bags, shoes, tents and the like.
2. Prior Art
A typical example of slide fastener having coupling elements made of a thermoplastic resin is disclosed for example in Japanese Patent Publication No. 58-13166. This prior art and other known slide fastener elements still have much to be desired in respect of smoothness with which they are coupled and uncoupled by a slider.
To provide a row of discrete resinous coupling elements on each of a pair of stringer tapes, there is used a split molding machine comprising an upper (stationery) mold and a lower (movable) mold having a longitudinal core strip. On opposite sides of this core strip are formed a multiplicity of mold cavities for receiving and shaping a hot molt of thermoplastic resin into respective individual coupling elements to be attached to and along a longitudinal, usually beaded edge of the stringer tape. The stringer tape or tapes upon hardening of the resin thereon are pulled out from the molds with a pulling force large enough to peel the shaped coupling elements off the core strip, in which instance the pulling force would often be so large that irregularities occur in the interspace or pitch of the coupling elements, resulting in malfunctioned slide fastener.